1. Field of the Invention
The present invention relates to an imaging lens that forms an optical image of a subject on an imaging device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), and an imaging apparatus such as a digital still camera that performs photographing with the imaging lens mounted therein, and a portable terminal device such as a cellular phone equipped with a camera and a portable information terminal (PDA: Personal Digital Assistance).
2. Description of Related Art
In recent years, as personal computers have become popular in homes, digital still cameras which are capable of transferring image information about photographed scenes, persons, and the like into the personal computers have spread rapidly. In addition, the incorporation of a camera module for inputting images into a cellular phone has been increasing. In these imaging apparatuses, imaging devices such as a CCD and a CMOS are used. In such imaging apparatuses, recently, because the imaging device has been reduced in size, a reduction in size of the whole of the imaging apparatus and an imaging lens mounted therein has also been required. Also, since the number of pixels included in the imaging device has also been increasing, the enhancing of the resolution and performance of the imaging device has been required. In order to cope with the requirements, in the past, an imaging lens was developed which was configured to have a total of four lenses. In contrast, recently, there is a tendency of increasing the number of lenses in order to achieve higher resolution and higher performance.
Japanese Patent No. 3788133, JP-A-2007-264180, and JP-A-2007-279282 disclose imaging lenses in which high performance is achieved by using five lenses. However, recently, further high performance has been required even for the disclosed imaging lenses.